Is Property Behaviors considered for Stage 1?
Because the project roadmap says:
The high-priority features supporting Stage 1's source and ABI stability
Resilience: resilience provides a way for public APIs to evolve over time,
while maintaining a stable ABI. For example, resilience eliminates the fragile
base class problem <https://en.wikipedia.org/wiki/Fragile_base_class> that
occurs in some object-oriented languages (e.g., C++) by describing the
types of API changes that can be made without breaking ABI (e.g., "a new
stored property or method can be added to a class").
And i think this feature will help with that. Not a complete solution for
resilience problem, but "provides a way for public APIs to evolve over time